 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.core.commands;

 /**
  * <p>
  * A listener to changes in some state.
  * </p>
  * <p>
  * Clients may implement, but must not extend this interface.
  * </p>
  *
  * @since 3.2
  */
 public interface IStateListener {

     /**
      * Handles a change to the value in some state.
      *
      * @param state
      * The state that has changed; never <code>null</code>. The
      * value for this state has been updated to the new value.
      * @param oldValue
      * The old value; may be anything.
      */
     public void handleStateChange(State state, Object oldValue);
 }

